Spark gap



1957 J. H. JOHNSTONE, JR 2,778,967

SPARK GAP Filed May 16, 1952 INVENTOR. JOHN H. JOHNS TONE AUTO/QA/EV United States Patent 1 2,778,967 SPARK GAP John H. Johnstone, Jr., Paramus, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application May 16, 1952, Serial No. 288,258 2 Claims. (Cl. 313-148) The invention relates to spark gaps or impulse gaps and more particularly to spark gaps or impulse gaps adapted for use in high frequency ignition systems for converting a relatively low frequency source to high frequeney.

The main object of the present invention is to provide a novel spark gap wherein the space between the electrodes may be varied to change the characteristics of the spark gap.

Another object is to provide novel structure for adjusting the electrode spacing.

The invention contemplates a spark gap comprising a sealed envelope having one of its Walls formed by a flexible diaphragm. A bridge is secured to the envelope exteriorly thereof adjacent the diaphragm. A pair of electrodes are positioned Within the envelope and one of the electrodes is mounted on the diaphragm. Means secured to the diaphragm and cooperating with the bridge is provided for adjusting the last-mentioned electrode to vary the space between the electrodes and to positively hold the electrode in adjusted position.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only, and is not intended as a definition of the limits of the invention.

In the drawing:

Figure l is a perspective view of a spark gap constructed according to the invention.

Figure 2 is a transverse section taken through the axis of the spark gap approximately on the line 2-2 of Figure 3, and

Figure 3 is an end view of the spark gap.

Referring now to the drawing for a more detailed description of the novel spark gap of the present invention, the spark gap is shown as comprising a cylindrical envelope 1 of glass or other suitable material closed at one end by a plate 5, having an evacuation tube 7 substantially centrally thereof. The plate may be of Kovar so that it may be readily sealed to the glass, as shown and described in Scott Patent No. 2,217,421 issued October 8, 1940. A spacer 9 is secured to plate and mounts an electrode 11 preferably of a refractory metal, such as tungsten.

The other end of envelope 1 is closed by an assembly consisting of a substantially cylindrical member 13 having a flange 15 sealed to the glass cylinder. The member 13 may be of Kovar also so that it may be readily sealed to the glass, as described in the above-mentioned Scott patent. A diaphragm 17, which may be of Kovar also, is secured to member 13 by Welding, brazing or other suitable means and a spacer 19 of steel or other suitable material is secured to one side of the diaphragm Within the envelope and mounts an electrode 21, preferably of a refractory metal such as tungsten. The opposing faces of the electrodes are positioned parallel to one another. The envelope may be filled with air or any suitable gas at a suitable pressure to provide a desired breakdown voltage.

An element 23 having a threaded shank 25 is secured Patented Jan. 22, E957 Hce to the other side of diaphragm 17 exteriorly of the envelope. A bridge 27 is secured to diametrally opposed points of flange 15 of member 13 and extends transversely of the envelope. An adjusting member 29 is threaded on shank 25 and extends through an aperture 31 in bridge 27. A lock nut 33 is threaded on adjusting member 29.,

Electrode 21 may be adjusted relative to electrode 11 by rotating adjusting member 29 on threaded shank 25 with a wrench or other suitable means which fits a hexagon portion 35 on the adjusting member. When electrode 21 is spaced at desired distance from electrode 11, electrode 11 may be locked securely in adjusted position by tightcning lock nut 33 so that bridge 27 is securely locked between the lock nut and hexagon portion 35 of the adjusting member.

The arrangement described provides for adjusting the electrode spacing without requiring rotating seals and positively holds adjustable electrode 21 in position relative to fixed electrode 11.

Although but one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts Without departing from the spirit and scope of the invention, as will now be understood by those skilled in the art.

What is claimed is:

1. A spark gap comprising a sealed envelope having one of its walls formed by a flexible diaphragm, a bridge secured to said envelope exteriorly thereof and positioned adjacent said diaphragm, a pair of electrodes within said envelope, one of said electrodes being rigidly supported within said envelope and said other electrode being movable with said diaphragm, a conductive spacer connecting said movable electrode with said diaphragm, and means for adjusting said last-mentioned electrode comprising a threaded shank fixed to said movable electrode and extending exteriorly of said envelope, an adjusting member threaded on said shank and engaging said bridge, and a lock nut threaded on said adjusting member and adapted to lock said bridge between said nut and said member to positively hold said adjustable electrode against movement in opposite directions and in adjusted position relative to said fixed electrode.

2. A spark gap comprising a sealed envelope formed of a glass cylinder closed by a cap at one end and by a diaphragm at the opposite end, electrodes mounted Within said envelope on said cap and on said diaphragm respectively, means for adjusting the electrode mounted on said diaphragm relative to the other electrode comprising a threaded shank fixed to said electrode and extending exteriorly of said envelope, a bridge secured to said envelope and positioned adjacent said diaphragm and having an aperture receiving said shank, an adjusting member threaded on said shank and engaging said bridge, and a lock nut threaded on said adjusting member and adapted to lock said bridge between said nut and said element to positively hold said adjustable electrode against movement in opposite directions and in adjusted position relative to said fixed electrode.

References Cited in the file of this patent UNITED STATES PATENTS 1,569,684 Schwerin Jan. 12, 1926 2,025,461 Leonard Dec. 24, 1935 2,412,659 Thomas Dec. 17, 1946 2,416,318 Hotine Feb. 25, 1947 2,435,316 Larson Feb. 3, 1948 2,440,154 Oles Apr. 20, 1948 2,540,399 Linkroum et a1 Feb. 6, 1951 2,566,704 Leibing Sept. 4, 1951 

